The term “electronic device” refers to a device that performs a specific function according to an equipped program, such as an electronic scheduler, a portable multimedia reproducer, a mobile communication terminal, a tablet PC, an image/sound device, a desktop/laptop PC, or a vehicular navigation system, including home appliances. For example, such an electronic device may output information stored therein as sound or an image. As the degree of integration of such electronic devices has increased, and super-high speed and large-capacity wireless communication has become popular, various functions have recently been provided in a single mobile communication terminal. For example, various functions, such as an entertainment function (e.g., a game function), a multimedia function (e.g., a music/video reproducing function), a communication and security function for mobile banking, a schedule management function, and an e-wallet function, are integrated in a single electronic device, in addition to a communication function.
A portable-purpose electronic device (e.g., an electronic scheduler, a portable multimedia reproducer, a mobile communication terminal, or a tablet PC) is generally equipped with a flat display device and a battery. In recent years, as the performance of a display device and a battery has been improved, electronic devices, which are miniaturized to be capable of being worn on a part of a human body, such as a wrist or a head, have appeared.
There are various kinds of input devices of such electronic devices. For example, a desktop computer or the like includes an input device, such as a keyboard or a mouse, and a home appliance may be provided with a remote-control device. In an electronic device, such as a mobile communication terminal, a microphone, or a keypad is used as a conventional input device, and in a laptop computer, a touch pad is used as an input device to replace a mouse. Such a touch pad may be typically realized in an electrostatic capacitance type to be capable of detecting a touch of a user's body (e.g., a finger).